The present invention relates to a reciprocating piston engine, and particularly to an internal combustion engine including a pair of counter-rotating crankshafts.
Conventional multi-cylinder high speed internal combustion engines small enough for use in automobiles, motorcycles, and smaller applications typically utilize a single crankshaft connected to all the pistons through connecting rods. One end of the crankshaft is connected to deliver power from the engine through a clutch or torque converter. Such a crankshaft may include counterweights to balance the pistons and connecting rods, and must have sufficient torsional stiffness to withstand the torque developed by the engine. The rotating mass of the crankshaft, particularly at high speeds, results in gyroscopic forces that can significantly affect the handling characteristics of vehicles, particularly motorcycles, in which such engines are used. Any imbalance in such an engine can result in significant vibration. The engine""s crankcase and cylinder block structures must therefore be sturdy enough to absorb such vibrations as well as the torque and power developed by the engine in operation.
In order to minimize the gyroscopic effects of a crankshaft, it has been known in the past to provide a pair of counter-rotating side-by-side crankshafts in an engine, with each crankshaft connected to each piston by at least one connecting rod, as shown in Hammerton, U.S. Pat. No. 5,435,232, and Wittner, U.S. Pat. Nos. 5,682,844 and 5,873,333, for example. Wittner discloses such an engine that the inventor claims is desirable for motorcycles because the crankshafts are located close together, resulting in a relatively narrow engine. Such engines, however, are of complex and costly construction.
What is desired, then, is an engine that can safely operate at high speeds, without the undesired gyroscopic effects and problems of vibration found in previously known engines, and that is not overly complex.
The present invention supplies an answer to the aforementioned shortcomings of previously known engines, by providing an engine in which a pair of counter-rotating crankshafts are aligned generally end-to-end.
In one preferred embodiment of such an engine, a plurality of cylinders are arranged generally in line with each other, with a respective piston disposed reciprocatingly within each cylinder, and with each piston connected with a respective one of the counterrotating crankshafts.
In one preferred embodiment of the invention the crankshafts are located coaxially with respect to each other.
In another preferred embodiment of the invention gears mounted on the adjacent ends of the crankshafts are meshed with each other to provide for opposite rotation of the crankshafts.
The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.